Friction reducing compositions for oil-based fracturing fluids



O United States Patent [1|13,542,044 [72] Inventors Gerald D. Hansen [50] Field of Search 252/8.5C,

fl li n 8.55A; 166/421, 308; 137/13 Leonard J. Persinski; Alan Bischo'f; John J. Padden, Pittsburgh, Pennsylvania [56] References (med [21] Appl. No. 588,655 UNITED STATES PATENTS [22] Filed Sept. 22, 1966 3,017,351 l/1962 Scott et a1 L 252/85 [45] Patented Nov. 24, 1970 3,122,203 2/1964 Hawkins l66/44X [73] Assignee Calgon Corporation, 3,215,154 11/1965 White et a1. 2$2/8.55X a corporation of Delaware. by mesne 3,254,719 6/1966 Root 166/42 assignments 3,3 78,074 4/1968 Kiel 137/13X a Primary Examiner- Herbert B. Guynn [54] FRICTION REDUCING COMPOSITIONS FOR OIL- BASED FRACTURING FLUIDS 4 Claims, No Drawings [52] [1.8. CI. 137/13, 1 166/308, 252/855 [51] 1nt.Cl. Fl7d l/l6, E21b 43/26 Attorney-William L. Krayer comprises adding to said oil in aqueous polyacryiamide solution preferably containing a dispersing agent.

This invention relates to compositions useful for enhancing the flow of oil-based fluids. Specifically, it relates to compositions containing polyacrylamide, a dispersing agent, and other compounds, and to the reduction of; fluid flow friction therewith. It is particularly useful in the reduction of friction loss in fracturing oil field-formations.

In an oil well fracturing operation, a fracturing fluid, is forced down a well bore hole under high pressure and at high flow rates, causing the rock formations surrounding the well bore to fracture. The pressure is then relieved, allowing the oil to seep through the fractures into the well bore where it is pumped to the surface. Almost any liquid may be used as a fracturing fluid; forexample, one may use water, brine or crude oil produced from nearby wells, This invention relates only, to oil-based fracturing fluids, which are fluids such as oil, crude oil, treated oil kerosene, diesel oil, and the like orany of these fluids in combination with water or brine.

The amount -of oil which can be obtained from a well, particularly in secondary recovery, depends to a great extent upon how extensively the rock formations can ,be fractured. This, in turn, depends in part upon the rate at which fluid can be pumped into the fractured porous rock formation. Due to friction between the fracturing fluid and theoil well piping or rock and in the fracturing fluid itself because of turbulent flow, the fluid flow rate attainable with a given pump pressure may be considerablyless than is desirable. Much of theenergy input to the pump is lost before the fracturing. fluid ever reaches its point of use. This problem is attacked by adding a friction reducer to the fracturing fluid. See, for example, Smith, Seichter, and Adler, U.S. Pat. No. 3,102,548; Dever, Harbour and Seifert, U.S. Pat. No. 3,023,760; Miller and Willson U.S. Pat. No. 3,105,047; and Clark and Shapiro, US. Pat. No. 2,533,878. A good friction reducer will cause a large decrease in friction in smallconcentrations, will be inexpensive, and will have high shear, temperature, and pressure stability.

An oil-based friction reducer in common use today is high molecular weight polyisobutylene. Polyisobutylenes are not readily dispersible and are sensitive to shear and high temperature so that dissolution by heating andstirring will cause them to lose effectiveness as friction reducers. Also,,the maximum friction reduction attainable is not very high and it varies widely under differing conditions.

Progress toward finding areally effective friction reducing compound for oil'has been retarded by the common assumption that such'a compound should be soluble in oil and other hydrocarbons. We have found, however, that a polymer-based friction reducing compound need not beoil soluble.

We have formulated compositions which are very useful for reducing friction in oil-based fracturing fluids. Our basic composition consists of about 85 percent to,99.8 percent water, about 0.l percent to 10 percent polyacrylamide,.and about 0.1 percent to 10 percent dispersing agent; preferably, it consists of about 96-99 parts'by weight water,.about l.3 parts polyacrylamide, and about 0. 1 1 5 parts dispersing agent. We have found that the use ofa quantity ofwater and a dispersing agent with polyacrylamide produces an oil-compatible system. The polyacrylamide should be ofa high molecular weight, preferably, at least 3 million. lt should also have about 5 percent to about 40 percent or more (preferably 35 percent) of its amide groups hydrolyzed to carboxylic groups. This may be accomplished by treatingthe polymerwith caustic as is known in the art.

The dispersing agent is an anionic or nonionic surface active agent. Examples of commercially available dispersingagents include Pluronic L-8l Aromox T-l2", Brij 35", and Span 60". Any nonionic dispersing agent may be used. Exam ples of commerciallyavailablematerials which may be used are listed in the following table.

Trademark Manufacturer Chemical Structure Span Atlas Chemical Ind. Sorbitan monooleate. Atpet 200. do- Sorbitan partial fatty esters. Arlacel (1 do Sorbitan sequioleate. Tween do Polyoxyethylene sorbitan trloleate. Tween 81 ..do Polyoxyethylene sorbitan monooleate. Tween 20 do Polyoxyethylene sorbitan monolaurate.

Tween 80 do Polyoxyethylene sorbitan monoolcate. Myr 52 do Polyoxyethylene stearate. Renex 697 do Ethoxylated nonyl phenol. Atlas 01-3284. do Polyoxyethylene 'sorbitol tallow esters.

Myrj 45 "do Polyoxyethylene stearate.

Atlas G-1086 do- Polyoxyethylene sorbitol hexaoleate.

Arlacel 80 .do. Sorbitan monoleate.

Triton X- Rohm & Haas C Is'ooctyl phenyl polyethoxy ethanol.

Pluronic L103; Wyandotte Chem. A condensate of ethylene L-92; L-81; Corporation. oxide with a hydrophobic L-lOl; L-61; base formed by condensing L-72; F 108. propylene oxide with propylene glycol.

Brij .30 Atlas Chem. Ind. Polyqoxyethylcno (4) lauryl et er.

11-77 Union Carbide... Organo Silicone.

FC-176 3M Flurocarbon.

Arosurf EO-74- Archer-Danlels- Long chain fatty alcohol l idland. ethylene oxide.

Syn-O-Tol LO80 Drew Chemical Co Linoleic diethanolamide.

Span 60 Atlas Chemical Ind. Sorbitan monostearate.

Renex 31- do Polyoxyethylene ether alcohol.

Poesho. do Polyoxyethylenc sorbitol hexaoleate.

We have performed experiments whichdemonstrate the effectiveness of our basic composition in reducing friction in oilbased fluids. In these experiments, 10 liters of oil-based fluid was continuously circulated at essentially constant flow rate and in highlyturbulent flow through :a 7-foot steel pipe having a 0.259 inch l.D. By means of gauges near eachend of the pipe, the, pressure drop between the gauging points was graphically recorded.A quantity of one of our basic compositions was added to:the.oil-based fluid and the decrease and subsequent return to normal of the pressure drop was recorded. Theamount by which pressuredrop decreases is recorded as a percentage of the normal value. Unless otherwise stated, theexamples and tables herein show results obtained with this procedure.

Table I gives the results of experiments on kerosene. Stability is the length of timethatthe friction reduction remained over 50 percent.

TABLE I.-FRICTION REDUCTION USING BASIC COMPOSITION [10 literskerosene, 3 gm. polyacrylamide (35% hydrolyzed) 300 ml. H20] Dispersing agent Maximum fric- Pluronic L-8l is a block polymer of polyoxyethylene and polyoxypropylene, a product of Wyandotte Chemicals Cor-.

poration; Aromox T-12 is bis(2-hydrcxyethyl)alkayl-amine I oxide.

Table ll demonstratesfthat various be used.

types of dispersants may Maximum percent friction reduction TABLE II [Efiect of Various Dispersant Types on the Friction Reducing Properties of Experimental Friction Reducer in 4 Gal. of Kerosene] Grams Milliter Polyacryl- Isopropyl amide alcohol Glycerol Water D 15p orsant Run No. Dispersant TABLE IV.-FRICTION REDUCING PROPERTIES (gifiXPERIMFEjNTAL FRICTION REDUCER IN CltUbE -cont|nuc Friction reducer formulation, grams Maximum Time to reach API Poly- Aromox Pluronic Ml. percent friction of max ercent Crude oil gravity acrylamide 'I12 L-Sl Calgon water reduction iric. radtiit/min.

AB 42. 0 9. 1 3. 03 3. 03 455 71 57 Golden Frac Oil 25. 5 9. 1 3. 03 3. 03 455 19 9. 1 3. 03 3. 03 455 30 9 9. 1 1. 50 3. 03 455 64 2 1; 01; 455 67 6 O 455 67 30+ Graybm'g 1 9. 1 a. 03 6.06 455 68 7o 9. 1 1. 50 6. 06 455 66 75 9. 1 3. 03 6. 06 455 68 83 3. i 6. 06 4425 52 66 5 54 10 Queens 9. 1 3 03 455 as as Norms:

(1) All runs are with dispersator on powerstet setting 85. (2) Formulations as shown were mixed into 4 gallons of base fluid.

We have found that the effectiveness of our basic composition may be increased by adding a coupling agent to it.

Our coupling agent composition consists of about 90 percent to 98.4'percent watenabout 0.1 percent to 10 percent polyacrylamide about 0.1 percent to 10 percent dispersing agent, and about 1.4 percent to 14 percent coupling agent; preferably it consists ofabout 95 percent to 99 percent water, about 1 percent to 3 percent polyacrylamide, about 0.1 percent to lpercent dispersing agent, and about 3 percent to 8 percent coupling agent. A coupling agent is a compound which has an affinity for both water and an oil-based fracturing fluid. We prefer a monofunctional alcohol having 3 to 5 carbon atoms or a polyfunctional alcohol; Examples of coupling agents include; isopropyl alcohol, glycerine, polyvinyl alcohol and ethanol.

Alternately stated, our composition may comprise: Parts by Weight Water c 200-500 Isopropanol 60 40 Glycerine 5-65 Dispersing Agent 0. 1-17 Sodium metaphosphate Up to 10 Experiments similar to those already described were performed using our coupling agent composition. Table V gives the results of these experiments where kerosene was the oilbased fluid, and Table VI gives the results where crude oil was Hydrolyzed polyacrylamide used.

TABLE V.FRIOTION REDUCTION USING COUPLING AGENT COMPOSITION [10 l. kerosene] Coupling agent Dispersing agent Maximum Polyacrylamide friction hydrolized 35% Water Quantity Quantity reduction Stability (gm/10 l.) (ml./10 1.) Type (ml./10 1.) Type (gm./101.) (percent) (min.)

Pluronic L-81 S 300 PVA 165 1 {Ammox T42 50+ 200 165 Isopropanol. 12 72 90+ 330 .do 12 73 120+ 110 I do.. 1 8 66 32 sopropano 11o {GlycemL s as so 220 Isopropenol. 16 70 165 do 16 68 55 11 50 135 Poepop2 10 65 65+ 120 Poesho 16 64 45 90 d0 8 65 45 J0 do 8 65 45 i 2g m. i NOTES: PVA-IGS is polyvinylacetate alcohol, a productoi Air Reduction. Poepop-2 is 10% polyoxyethylene, 90% polyoxypropylene (medium molecular weight), a product oi Atlas Chemical Ind.

TABLE VL-FRICTION REDUCTION USING COUPLING AGENT COMPOSITION [101. crude oil] Coupling agent Dispersing agent Maximum Polyacrylamide friction hydrolized 35% Water Quantity Quantity reduction Stability m./10l (ml./10 1.) Type (ml./1O 1.) Type (ml./10 1.) (percent) (min.) 3 100 Glycerol 50 Aromox T-l2.. 1 54 35 5 {Pluronie L-81 1} 52 35 Aromox 'I12 0. 5

20 Pluronic L81 I 56 70 Most oil-based fracturing fluids contain small concentrations of various polyvalent cations, especially calcium. Since cations sometimes interfere with the effectiveness of our compositions in reducing friction, it is desirable to include about 0.1 percent to 1 percent compatible chelating agent in both the basic and coupling agent compositions; preferably, about 0.3 percent to 0.4 percent chelating agent is included. This chelating agent should prevent the interference of polyvalent cations and should not itself interfere. Examples of such chelating agents include ethylenediamine tetra acetic acid, sodium hexametaphosphate, and sodium salicylate; sodium hexametaphosphate is preferred. 2 5

Experiments similar to those already described were performed using a chelating agent in addition to the other ingredients of the compositions. Table V shows the results of experiments on kerosene and Table VI on crude oil where the l basic composition was used, and Tables VII and VIII show the results of experiments on kerosene and crude oil respectively, where the coupling agent composition was used.

Dispersing agent Sodium Maximum Polyacrylamide hexametafriction hydrolyzed Water Quantity phos hate reduction Stability (gm./10 l.) (ml./10 1.) Type (gm./10 1.) (gm. 10 1.) (percent) (minJ Pluronie L81 2 6 300 {Aromox T12 2 2 66 300+ TABLE VIIL-FRICTION REDUCTION USING BASIC COMPOSITION [101. crude Oil] Dispersing agent Sodium Maximum Polyacrylamide hexametafriction m hydrolyzed 35% Water Quantity phosphate reduction Stability ,1 (gm. 101.) (mL/IO l.) Type (gm. 101.) (gm./10 1.) (percent) (mind Pluronic L81 1 300 {i l 1512"" 3 53 55 uronie 81 1 i a mmox 0. a 3 52 uronic 81 1 500 {Aromox T12 0.3 3 54 60 300 Renex-31 I 3 54 30 300 Pllilronic I021 1 3 54 35 uronic 8 1 Surfonic .TN70. 1 i 3 54 55 300 Surfonic J'N70 2 3 55 35 300 Ag}ox1%56i; 8 1 3 53 40 uron c i. 1 200 {Arornox T12 0.3 i 3 56 300 Prl uronic Ill-15L." 0.8 3 56 uronic 8l 0.3 300 {Aromox T12. 0.3 i 2 53 40 500 Pluronic'L-81 I 2 54 300 .i ludonufjgffl 0.5 3 58 55 uronic 8 300 {Aromox T12 8 i 10 58 Renex-3l is a polyoxyethylene ester 01 mixed fatty and resin acids, :1 product of Atlas Chemical Industries. C Pluronic L-J2 is a block polymer of polyoxyethylenc and polyoxypropylone, a product oiJeflerson Chemical .ompany. Surfonic J N-70 is u primary alcohol-ethylene oxide adduct, a product of Wyandottc Chemicals Corporaon.

I d Apex-1256 is n polyoxyethylenc sorbitol ester of mixed fatty and rosin acids, :3. product of Atlas Chemical n us nos.

TABLE IX.-FRICTION REDUCTION USING COUPLING AGENT COMPOSITION [10 l. kerosene] Coupling agent Dispersing agent h Sodiipu Maziriingim exame ac o Polyacrylamide hydrolyzed Water Quantity Quantity phosphate reduetior i Stability 35% (gm./10 l.) (m1./10 1.) Type (ml./10 1.) Type (gm./10l.) (gm./l 1.) (percent) (min.)

300 Glycerlne 10 PluronicL-Bl-.. 1.0 3. 56 75 TABLE X.-FRICTION REDUCTION USING COUPLING AGENT COMPOSITION [101. crude oil] Coupling agent Dis ersin a ent Sodi Ma Polyacrylamide hydrollzed Water (ml./ p g g hexarne t Stability (gm/10 l.) 10 1.) Quantity Quantity phosphate reduction (min.)

Type (ml.,10 1.) Type (gin/101.) (gm/101.) (percent) Pluronlc L81 1 s00 Glycerol 1o {Ammox 0 3 5s 70 glluronlo 1 3 53 moms 1 10 ifomixi TI412in 0.5 i d 56 uron c -8 1 10 {Arorno r T12i 0.5 i 3 54 60 300 Carbowax6000 i 3 53 60 300 Is0propanol 3 55 Pluronio L-81 1 300 Glycerol so {Ammox Q5 a 56 190 10 11:}uronio:81 1 3 54 95 uronic 81... 1 1O {Aromox T12 0.5 i 3 54 105 NoTE.-Carbowax6000 is a polyethylene oxide polymer, :3. product of Union Carbide Generally, about 1 percent to 10 percent of our composition is added to the oil-based fracturing fluid; preferably, about 3 percent to 5 percent is added. Satisfactory results are obtained when the water is added before the other ingredients.

Many oil-based fracturing fluids contain a fluid loss additive such as Adomite Mark ll", a product of Continental Oil Company. Our compositions function equally as well in the presence of these additives.

Our invention is not restricted to the specific examples and illustrations recited herein. It may be otherwise variously prac ticed within the scope of the following claims.

We claim:

1. Method of inhibiting energy loss during the turbulent flow of a hydrocarbon fluid through a pipe comprising emusifying in said hydrocarbon fluid from about 1 to about 10 per cent by weight ofa composition comprising:

a. about 85 percent to 99.8 percent water;

b. about 0.1 percent to about 10 percent polyacrylamide having a molecular weight of at least 3 million; and

c. about 0.1 percent to about 15 percent dispersing agent from the group consisting of anionic and nonionic surface active agents effective for emulsifying said composition in said hydrocarbon fluid.

2. Method of claim 1 in which about 5 percent to about 40 percent of the amide groups in the polyacrylamide are hydrolyzed.

3. Method ofclaim l in which the composition comprises:

a. about 96 percent to about 99 percent water;

1). about 1 percent to about 3.9 percent polyacrylamide having a molecular weight of at least 3 million; and

c. at least about 0.l percent of the dispersing agent.

4. Method of claim 1 in which a small amount ofa coupling agent selected from the group consisting of monofunctional alcohols having 35 carbon atoms and polyfunctional alcohols selected from the group consisting of glycerine and polyvinylalcohol is also added to the oil. 

